two boot data volumes after clean reinstall of Catalina and Time Machine will not do backups anymore

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Level 1

18 points

two boot data volumes after clean reinstall of Catalina and Time Machine will not do backups anymore

After reinstalling Catalina from scratch on my Mac mini 2012, I now found two identically named "Mac mini Boot-Data" volumes. In Disk Utility, I can see the smaller volume, about 250Gb, has the hard disk icon adorned with a little house at the lower right corner and is marked "macOS 10.15.2". The larger volume, at 1.01TB, has the plain icon only. Both are APFS volumes and the larger volume seems to overlap the smaller one.

Time Machine now refuses to do backups due to the duplicated volumes. Everything else seems to work just fine, though.

Mac mini, macOS 10.15

Posted on Dec 23, 2019 5:22 PM

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Answer 1

Best reply

i_rina

Community Specialist

Dec 26, 2019 6:55 AM in response to firelion

Hello firelion!

Welcome to and thanks for using the Apple Support Communities!

I understand from your post that after re-installing Catalina on your Mac mini, Disk Utility is showing duplicate "data" volumes" which is preventing you from creating a Time Machine back up.

Try testing this issue in safe mode and in a new user account following the steps in these articles based on how your Mac responds:

Use safe mode to isolate issues with your Mac

How to test an issue in another user account on your Mac

If the issue continues to persist, I recommend that you contact Apple Support.

Kindest Regards.

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Answer 2

keg55

Level 6

11,743 points

Jan 14, 2020 6:55 AM in response to firelion

This has happened to me when I did not remove both the Catalina and Catalina - Data volumes from their Container prior to reinstalling Catalina. When I just erased both, that's when I got a 2nd Data volume. Just remember to remove both volumes before doing a clean install.

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Answer 3

firelion Author

Level 1

18 points

Jan 14, 2020 6:47 AM in response to i_rina

I renamed the larger data volume to "old" and now Time Machine is working. However, I still don't understand why Catalina created the new data volume and name it the same to cause the problem.

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two boot data volumes after clean reinstall of Catalina and Time Machine will not do backups anymore

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